Project Abstract

<p> </p><p>Human whole blood samples obtained from blood banks in different hospitals in<br>Enugu State were analyzed for cadmium, lead and chromium concentrations<br>using atomic absorption spectrophotometric method. The results of the analysis<br>showed that about 72.7% of the samples had cadmium concentrations more<br>than the limit of safe exposure (5ug/l of blood). Also about 18.2% of the<br>samples had the concentrations of lead to be more than the maximum<br>permissible limit in adult human blood which is 300ug/l. On the other hand,<br>chromium concentrations in all the samples were within the range of its safe<br>exposure as it is a micro nutrient in man. The concentrations of cadmium and<br>lead could be indicative of both environmental and occupational exposure<br>hazards.</p><p>&nbsp;</p> <br><p></p>

Project Overview

<p> 1.0 INTRODUCTION<br>11 Environmental Pollutants<br>Human beings have significant impact on the environment especially now<br>that there has been much increase in human population. The increase in<br>population had led to corresponding increment in human activities like<br>industrialization, transportation, mining and agricultural processes which<br>generate different substances that can influence the environmental make ups<br>negatively. When these occur, our environment is said to be contaminated or<br>polluted.’<br>Environment can be defined as the place surrounding an organism. It<br>includes both biotic (living) and abiotic (non living) factors that affect the<br>organism in the surroundings. Land (lithosphere), water (hydrosphere), and air<br>(atmosphere) make up our environment and these serve as the buckets where<br>wastes are channeled or disposed.<br>Environmental pollution is the introduction of harmful substances or<br>toxicants into the environment thereby making it (environment) unsuitable for<br>both plants and animals living in it. It can be in form of land, water or air<br>pollution and some of the pollutants have cumulative effects in both plants and<br>animals. These effects depend on the biological chemical, and physical<br>characteristics, concentrations of the toxicant in the environment, and can lead<br>to either death, ill-health or both2.<br>1.2 Trace Metals in Human Blood<br>In man, blood is one of the body fluids and serves as a medium for<br>toxicant distribution because it is connected to other tissues and organs in the<br>. body. The distribution of the toxicants occurs when they are ingested, inhaled or<br>absorbed through the skin. Human blood is made up of the solid cells or<br>corpuscles namely; red blood cells (erythrocytes), white blood cells (leucocytes),<br>and platelets (thrombocytes). The liquid portion of the blood where the cells are<br>suspended is called the plasma. Functions of blood include; distribution of<br>oxygen carrying pigment called haemoglobin, protection of the body against the<br>invasion of micro-organisms, formation of blood clots to prevent excessive blood<br>loss when injury occurs and so on. Other substances found in blood are mineral<br>salts, food materials, hormones etc. An adult man contains about 5.5 litres of<br>blood and this constitute about 7% of the total body eight.^<br>P.3 Sources and Effects of Trace Metals in Human Blood<br>Haematotoxicity is the state of blood contamination as a result of the<br>presence of toxicant(s) in it. This state of blood affects its quality or quantity<br>produced in the bone marrow. I t can be linked to malfunctioning of other tissues<br>like kidney, liver, lung, bone, and the peripheral and central nervous systems etc.<br>1<br>Heavy metals are those metals that have their densities to be more than<br>5g/cm3. They include; cadmium, lead, chronlium, mercury, arsenic, tin and so<br>on4. Some of them like cadmium, lead, arsenic and mercury are considered toxic<br>in man no mater their concentrations5. They are also called trace elements<br>because their concentrations in the natural environment are low. Among these<br>elements, some are called essential elements in man because they are needed in<br>small quantities for different metabolic processes in the body e.g. chromium,<br>copper, zinc, iron, selenium etc.<br>The earth’s crust is the major source of cadmium, lead and chromium of<br>the various environmental systems. The rocks that form the soils were initially<br>subjected to various physical and chemical processes like erosion weathering.<br>Subsequently, soils and sediments became the terrestrial and aquatic substratum<br>for plants which absorbed, translocate and in some cases bioaccumulate some of<br>these elements. These lead to the incorporation of these elements in man and<br>other animals when they consume the plants.<br>Water gets contaminated with heavy metals through natural weathering<br>and leaching, and by dissolving and reacting with them. I t also mobilizes and<br>distributes them to different sites. Volcanic activity, forest fire, soil dusts and salt<br>sprays bring about both aerosols and particulates which are the major sources of<br>the metals to the atmosphere5. Some quantity of these elements in the<br>atmosphere can deposit on the plants, soil, water or can be inhaled directly by<br>human beings and other animals thereby increasing the concentrations of the<br>metals in the body.<br>As the effects of cadmium, lead and chromium are cumulative, they<br>accumulate in target organs and soft tissues like kidney and liver thereby causing<br>4<br>some impairment in the functioning of these organs. This is made possible<br>because of a protein called metallothionein found i<br>and lead bind to very strongly.<br>More concentrations of cadmium are found<br>liver while liver accuinulate most of the lead than<br>in soft tissues which cadmium<br>in the kidney followed by the<br>the other soft tissues. Equal<br>concentrations of chromium are obtained in kidney, liver and blood.<br>1.4 AIMS AND OBJECTIVES OF THIS PROJECT<br>This research is aimed at evaluating the extent of environmental pollution<br>by heavy metals in Nigeria. It is meant to ascertain quantitatively the<br>concentrations of cadmium, lead and chromium in the blood of adult Nigerians as<br>a result of their exposures to different environmental and occupational hazards.<br>Besides it is expected to serve as an eye-opener on environmental<br>degradation and will go a long way in enlightening the general public on the<br>importance of keeping good environment. This will inculcate good habits of<br>proper waste disposals in individuals. It is also targeted at making people<br>understand the problems associated with heavy metals and will help the public in<br>protecting themselves against the sources of these metals in order to reduce<br>pre-mature death and ill-health.<br>1.5 SCOPE OF THE STUDY<br>The scope of this study is quantitative determination of the concentrations<br>of cadmium, lead and chromium in human whole blood of adult Nigerians. The<br>modes of administrations, rates of accumulations, sources and speciations of<br>these metals in the blood samples are not included. <br></p>